The major objective of the proposed research is to establish whether heterogeneity at the gene loci for lysosomal acid lipase (LAL) and/or neutral cholesteryl esterase (NCE) activities results in hyperlipoproteinemia and predisposes it to early development of atherosclerosis in man. We will study patients and their families who have hyperlipoproteinemia and coronary artery disease thought to be monogenically or polygenically inherited. Lymphocytes from these patients and their families will be the primary enzyme source. The methods for studying LAL-A (the enzyme shown to be deficient in Wolman's disease and cholesperyl ester storage disease) were developed in our laboratory and include fluorometric assay and differential heat inactivation, isoelectric focusing and electrophoresis. Similar methodology will be used for the assay and characterization of neutral cholesteryl esterase. There is strong reason to believe that genetic reduction of these enzyme activities will predispose to hyperlipoproteinemia and premature atherosclerosis. We hope to identify families in which a variant of LAL-A or NCE, with reduced enzyme activity, co-segregates with the hyperlipoproteinemia and, if possible, identify patients homozygous for the variant. The biochemical properties of variants found in these studies will be characterized in fibroblast culture. In addition, we plan to characterize other lipolytic activities identified by isoelectric focusing in lymphocytes and determine whether genetic deficiency of any of these is associated with other rare forms of neutral lipid storage disease.